JP7089843B2 - Synthetic resin laminated foam sheet and its manufacturing method, food container - Google Patents

Description

The present invention relates to a synthetic resin laminated foam sheet having a foam layer, a method for producing the same, and a food container formed of the synthetic resin laminated foam sheet.

Conventionally, there is a polypropylene-based resin laminated foam sheet of Patent Document 1 as a synthetic resin laminated foam sheet having a foam layer. This polypropylene-based resin laminated foam sheet is obtained by laminating a polypropylene-based resin printing film composed of a polypropylene-based resin layer and a printing layer on a polypropylene-based resin foamed sheet by a thermal lamination method so that the printing layer is on the foamed sheet side. The peeling strength from the foamed sheet is 1.5 N / 25 mm or more.

The thickness of the polypropylene-based resin layer of the polypropylene-based resin printing film is described in claims 2 and 6 of Patent Document 1 in the left column, lines 19 to 24, from the viewpoint of preventing breakage of the film layer during heat molding and lightness. It is disclosed that the thickness is 15 to 100 μm, and further, in Patent Document 1, page 7, right column, lines 17 to 19, and Table 1, the thickness of the polypropylene-based resin printing film of all Examples 1 to 4 is set to 25 μm. It is disclosed that the peel strengths of Examples 1 to 4 were 2.3 N / 25 mm, 1.7 N / 25 mm, 2.1 N / 25 mm, and 2.5 N / 25 mm.

Japanese Patent Application Laid-Open No. 2003-300921

By the way, when food containing oil is contained in a food container molded of a synthetic resin laminated foam sheet, when the food container is heated in a microwave oven, the temperature of the food containing oil becomes high and the temperature is locally increased to 150 ° C. It may exceed the temperature. In such a case, if a food container formed from a resin laminated foam sheet on which the above-mentioned polypropylene-based resin printing film having a thickness of 25 μm is laminated and molded with the polypropylene-based resin printing film on the food side is used. Due to the thinness of the polypropylene-based resin printing film having a thickness of 25 μm, the heat generated by heating reaches the fixing interface of the film, causing peeling (derami) of the film.

The present invention has been proposed in view of the above problems, and when a high boiling point food such as a food containing oil is heated in a microwave oven with the non-foamed laminated film on the food side, the heat generated by the heating is applied to the fixing interface of the film. It is an object of the present invention to provide a synthetic resin laminated foam sheet capable of suppressing arrival and preventing peeling of a non-foamed laminated film, a method for producing the same, and a food container molded from the synthetic resin laminated foam sheet.

The synthetic resin laminated foam sheet of the present invention is a synthetic resin laminated foam sheet including a base material having a foam layer and a non-foamed laminate film laminated on the base material, and the non-foamed laminate film is one or more layers. This is a synthetic resin laminated foam sheet suitable for foods, characterized by having the polyolefin-based resin layer of the above, and having a total thickness of 40 μm or more of the polyolefin-based resin layer.
According to this, the polyolefin-based resin layer having a total thickness of 40 μm or more of the non-foamed laminated film can suppress the heat from reaching the fixing interface between the non-foamed laminated film and the base material due to heating. Therefore, even when a high boiling point food such as a food containing oil is heated in a microwave oven with the non-foaming laminate film on the food side, the heat due to the heating is suppressed from reaching the fixing interface of the film, and the non-foaming laminate film is prevented. It is possible to prevent peeling (derami) of the film. It should be noted that this is an effect different from that of Patent Document 1 for preventing the film layer from breaking during heat molding.

The synthetic resin laminated foam sheet of the present invention is characterized in that the peel strength of the non-foamed laminated film with respect to the substrate is 3.0 N / 15 mm or more.
According to this, it is possible to secure sufficient adhesive strength between the base material and the non-foamed laminated film, and when the food container is heat-molded with the synthetic resin laminated foam sheet, the non-foamed laminated film follows the base material well. It is possible to form a food container having a complicated shape without causing delamination. In the sheet having a peel strength of 1.5 N / 25 mm of Patent Document 1, when a food container having a complicated shape is molded when the food container is heat-molded, the non-foamed laminated film can follow the base material due to insufficient fixing strength. Desquamation may occur without. Further, by ensuring sufficient adhesion strength between the base material and the non-foamed laminated film, it is possible to more reliably prevent peeling (delamination) of the non-foamed laminated film even when heating in a microwave oven.

The synthetic resin laminated foam sheet of the present invention is characterized in that the base material has the foamed layer and a non-foamed surface layer laminated on one side or both sides of the foamed layer. For example, a base material composed of a foam layer, a non-foam surface layer laminated on one side or both sides of the foam layer, and a non-foam heat laminated film laminated on the non-foam surface layer of the base material. It is preferable that the non-foaming heat laminated film has one or more polyolefin resin layers, and the synthetic resin laminated foam sheet has a total thickness of 40 μm or more of the polyolefin resin layers, and further, the base material. It is more preferable that the peel strength of the non-foamed heat laminated film is 3.0 N / 15 mm or more.
According to this, for example, when the foam layer contains an inorganic filler, a meshi which is a residue of the inorganic filler is generated at the die mouth and easily becomes a foreign substance on the surface of the foam layer. However, for example, the inorganic filler is contained. The non-foamed surface layer makes it possible to extrude the foamed layer and the non-foamed surface layer at the same time, and it is possible to suppress or prevent the generation of shavings during manufacturing and the contamination of the molded product due to the shavings.

In the synthetic resin laminated foam sheet of the present invention, the base material is laminated on the foam layer, the non-foamed intermediate layer laminated on one side or both sides of the foamed layer, and the non-foamed intermediate layer laminated on the outside of the non-foamed intermediate layer. It is characterized by having a surface layer. For example, it contains a foamed layer, a non-foamed intermediate layer made of polypropylene containing an inorganic filler laminated on one side or both sides of the foamed layer, and an inorganic filler laminated on the outside of the non-foamed intermediate layer. The non-foaming heat-laminated film comprises a base material composed of a non-foaming surface layer made of polypropylene and a non-foaming heat-laminated film laminated on the non-foaming surface layer of the base material. It is preferable to use a synthetic resin laminated foamed sheet having one or more polypropylene resin layers and having a total thickness of 40 μm or more of the polypropylene resin layer , and further, the peel strength of the non-foamed heat laminated film with respect to the substrate. It is more preferable to set it to 3.0 N / 15 mm or more.
According to this, the required strength can be ensured for the sheet by the non-foaming intermediate layer, preferably the non-foaming intermediate layer made of polypropylene containing an inorganic filler . Further, when the non-foaming intermediate layer contains an inorganic filler, a shaving that is a residue of the inorganic filler is generated at the die mouth, and it is easy to become a foreign substance on the surface of the non-foaming intermediate layer, but for example, the inorganic filler is not contained. A non-foamed surface layer that does not contain an inorganic filler , such as a non-foamed surface layer made of polypropylene, allows for extrusion molding at the same time as the foamed layer, the non-foamed intermediate layer, and the non-foamed surface layer. It is possible to suppress and prevent the generation of shavings and the contamination of molded products due to shavings.

The method for producing a synthetic resin laminated foam sheet of the present invention is a method for producing a synthetic resin laminated foam sheet of the present invention, wherein the surface layer of the base material on the side to be fixed to the non-foamed laminate film is equal to or lower than the melting point of the surface layer. The base material and the non-expanded laminate film are thermally laminated by the first step of preheating to the temperature of the above and the heating roll heated to a temperature equal to or higher than the melting point of the polyolefin resin layer constituting the non-expanded laminate film. It is characterized by having two steps. For example, it contains a base material composed of a foam layer and a non-foamed surface layer laminated on one or both sides of the foam layer, or an inorganic filler laminated on one side or both sides of the foam layer and the foam layer. Regarding a base material composed of a non-foamed intermediate layer made of polypropylene and a non-foamed surface layer made of polypropylene which does not contain an inorganic filler laminated on the outside of the non-foamed intermediate layer, the above-mentioned material is described. The first step of preheating the non-foamed surface layer on the side where the base material adheres to the non-foamed heat laminated film to a temperature equal to or lower than the melting point of the non-foamed surface layer, and the polypropylene constituting the non-foamed heat laminated film. It is preferable to use a method for producing a synthetic resin laminated foam sheet, which comprises a second step of heat laminating the base material and the non-foaming heat laminating film with a heating roll heated to a temperature equal to or higher than the melting point of the resin layer .
According to this, by preheating the surface layer on the side to which the base material is fixed to a high temperature state in advance, it is possible to increase the bonding force and the fixing strength between the base material and the non-foamed laminated film by thermal laminating. .. Further, by improving the adhesion strength between the base material and the non-foamed laminated film, a more complicated food container can be molded from the synthetic resin laminated foam sheet without causing delamination.

In the method for producing a synthetic resin laminated foam sheet of the present invention, when the surface layer of the base material is the non-foamed surface layer, the non-foamed surface layer is made of a polyolefin resin having a melting point of 130 ° C. to 160 ° C. Features According to this, by using a polyolefin-based resin with a melting point of 160 ° C or less for the non-foamed surface layer of the base material, which is the surface layer on the side to which the base material adheres, an expensive facility capable of high-temperature thermal lamination can be provided. Even if it is not used, the bonding between the base material and the non-foamed laminate film by thermal laminating can be surely achieved with excellent bonding force and strength. Further, by using a polyolefin resin having a melting point of 130 ° C. or higher as this non-foamed surface layer, a non-foamed laminated film is formed when food is placed in a food container molded of a synthetic resin laminated foam sheet and heated in a microwave oven. It is possible to more reliably prevent the occurrence of peeling (derami).

The food container of the present invention is formed of the synthetic resin laminated foam sheet of the present invention, and the non-foamed laminated film is arranged on the food side. For example, it is suitable for a food container formed of the synthetic resin laminated foam sheet of the present invention and in which the non-foamed heat laminated film is arranged on the food side.
According to this, it is possible to make a food container having the effect of the synthetic resin laminated foam sheet of the present invention, and a high boiling point food such as a food containing oil is stored in the food container in which the non-foamed laminate film is arranged on the food side. Then, when heated in a microwave oven, it is possible to suppress the heat generated by the heating from reaching the fixing interface of the non-foamed laminated film, and the non-foamed laminated film is peeled off (derami) inside the food container. Can be prevented.

According to the present invention, when a high boiling point food such as a food containing oil is heated in a microwave oven with the non-foamed laminated film on the food side, the heat due to the heating is suppressed from reaching the fixing interface of the film, and the non-foaming laminated film is prevented from reaching the fixing interface. It is possible to obtain a synthetic resin laminated foam sheet or a food container that can prevent the foamed laminated film from peeling off.

The partial vertical sectional view which shows the synthetic resin laminated foam sheet of 1st Embodiment by this invention. A vertical cross section of a food container formed of the synthetic resin laminated foam sheet of the first embodiment. The schematic diagram which shows a part of the manufacturing equipment which manufactures the synthetic resin laminated foam sheet of 1st Embodiment. The partial vertical sectional view which shows the synthetic resin laminated foam sheet of 2nd Embodiment by this invention. The partial vertical sectional view which shows the synthetic resin laminated foam sheet of 3rd Embodiment by this invention. (A) is a partial vertical sectional view showing a synthetic resin laminated foam sheet of a first modification of the first embodiment, and (b) is a partial vertical sectional view showing a synthetic resin laminated foam sheet of a second modification of the first embodiment. figure.

[Synthetic resin laminated foam sheet of the first embodiment and its manufacturing method, food container]
As shown in FIG. 1, the synthetic resin laminated foam sheet 1 of the first embodiment according to the present invention includes a base material 2 having a foamed layer 21 and a non-foamed laminated film 3 laminated on the base material 2. be. The synthetic resin laminated foam sheet 1 is used as a material for a food container. For example, the food container 5 as shown in FIG. 2 is formed of the synthetic resin laminated foam sheet 1 so that the non-foamed laminated film 3 is arranged on the food side. To. The food container 5 is formed by heat-molding the synthetic resin laminated foam sheet 1 using a mold having a predetermined shape.

In the base material 2 of the synthetic resin laminated foam sheet 1 of the first embodiment, the non-foamed intermediate layers 22 and 22 are laminated on both surfaces of the foamed layer 21, and the non-foamed surface layer is formed on the outside of the respective non-foamed intermediate layers 22 and 22. It is formed by laminating 23 and 23. The foamed layer 21 is appropriate as long as it does not deviate from the gist of the present invention. Use a foaming resin or the like. Further, the non-foamed intermediate layer 22 is appropriate as long as it does not deviate from the gist of the present invention, but it is preferable that the non-foaming intermediate layer 22 can enhance the strength of the sheet 1, for example, polypropylene (PP) containing an inorganic filler such as talc. And so on. Further, the non-foamed surface layer 23 is appropriate as long as it does not deviate from the gist of the present invention, but it is preferable that the non-foamed surface layer 23 can suppress the shavings generated during sheet production, for example, with a polyolefin resin such as polypropylene (PP). do.

The non-foamed laminated film 3 laminated on the base material 2 has a polyolefin-based resin layer 31, and the polyolefin-based resin layer 31 is formed with a thickness of 40 μm or more. The thickness of the polyolefin-based resin layer 31 is preferably 40 μm to 80 μm, more preferably 45 μm to 70 μm. The polyolefin-based resin layer 31 is appropriate as long as it does not deviate from the gist of the present invention, and is, for example, polypropylene (PP) such as unstretched polypropylene (CPP). Further, in the non-foamed laminated film 3 of the first embodiment, the printing layer 32 and the coating layer 33 are laminated in this order on one side of the polyolefin resin layer 31. The print layer 32 is for coloring or patterning the sheet 1, and is composed of, for example, a urethane resin vehicle or the like. The coat layer 33 is appropriate as long as it facilitates adhesion of the non-foamed laminate film 3 to the base material 2. For example, when the base material 2 or the non-foamed surface layer 23 is polypropylene (PP), chlorinated polypropylene ( A PP) -based coating agent or the like is used, and a coating agent appropriately selected according to the material of the base material 2 or the non-foamed surface layer 23 is used.

The non-expanded laminated film 3 is laminated and fixed on the base material 2, and is fixed so that the peel strength of the non-foamed laminated film 3 with respect to the base material 2 is 3.0 N / 15 mm or more. This peel strength is measured according to JIS K 6854, and is the same in the second and third embodiments described later. In the first embodiment, the coat layer 33 of the non-foamed laminate film 3 is arranged adjacent to the non-foamed surface layer 23 on one side of the base material 2, and the coat layer 33 of the non-foamed laminate film 3 and the non-foamed base material 2 are non-foamed. The foamed surface layer 23 is fixed so as to be melted together.

When manufacturing the synthetic resin laminated foam sheet 1 of the first embodiment, for example, a heating roll 6 for heating the base material 2 and the non-foamed laminated film 3 shown in FIG. 3, and a preheating roll 7 for preheating the base material 2. , Conveying rolls 81 and 82 for transporting the base material 2, transport roll 83 for transporting the base material 2 and the non-foamed laminate film 3 so as to be sandwiched between the heating roll 6 and the base material 2 and the fixed synthesis. A manufacturing facility including a transport roll 84 for transporting the resin laminated foam sheet 1 is used.

Then, the non-foamed intermediate layers 22 and 22 are laminated on both surfaces of the foamed layer 21, and the non-foamed surface layers 23 and 23 are laminated on the outside of the non-foamed intermediate layers 22 and 22 to transport the base material 2 in an integrated state. The base material 2 is preheated by the preheating roll 7 located between the transport rolls 81 and 82 and the heating roll 6. This preheating is performed at a temperature equal to or lower than the melting point of the non-foamed surface layer 23 of the base material 2 so that the non-foamed surface layer 23 does not melt. The temperature of the preheating is preferably 50 ° C. or higher, more preferably 60 ° C. or higher in the non-foamed surface layer 23 of the base material 2. Further, at least one side of the non-foamed surface layer 23 on the side to be bonded to the non-foamed laminate film 3 described later or the base material 2 to be bonded to the non-foamed laminate film 3 is preheated. Here, it is preferable that the non-foamed surface layer 23 of the base material 2 is formed of a polyolefin resin having a melting point of 130 ° C. to 160 ° C., more preferably a polyolefin resin having a melting point of 135 ° C. to 155 ° C., further. It is preferably formed of a polyolefin resin having a melting point of 140 ° C. to 150 ° C. This melting point is measured according to JIS K 7121, and is the same in the second and third embodiments described later. In this case, it is preferable to preheat the preheating roll 7 so that the temperature of the preheating roll 7 is 100 to 140 ° C. and the temperature of the non-foamed surface layer 23 of the base material 2 is 80 to 120 ° C. The preheating is not limited to that by the preheating roll 7, and can be preheated by an appropriate method. For example, a heater is used to attach the preheating to at least the non-foamed laminate film 3 of the base material 2 being transported. The non-foamed surface layer 23 on the mating side or the one-sided side of the base material 2 on the laminating side with the non-foaming laminate film 3 can be preheated by a heater, and the same applies to the second and third embodiments described later. Is. Further, it is preferable that the preheating and transportation by the preheating roll 7 are performed immediately before the heating roll 6 in order to avoid a temperature drop of the base material 2.

After that, the base material 2 is sent out between the heating roll 6 and the conveying roll 83 by the conveying roll 82, and the non-foamed laminate film 3 is sent out between the heating roll 6 and the conveying roll 83 so as to be on the heating roll 6 side. The heating roll 6 and the transport roll 83 are laminated so as to sandwich the conveyed base material 2 and the non-foaming laminate film 3, and are heated by the heating roll 6 to heat-laminate the base material 2 and the non-foaming laminate film 3. do. The thermal laminating is performed by a heating roll 6 heated to a temperature equal to or higher than the melting point of the polyolefin resin layer 31 constituting the non-foaming laminate film 3, and the base material 2 and the non-foaming laminate film 3 are welded or adhered by this heating. The temperature of the heating roll 6 is preferably 170 ° C. or higher, more preferably 200 ° C. or higher, and is preferably 170 to 250 ° C., although it depends on the thickness of the base material 2 and the non-foamed laminated film 3 and the pick-up speed for these. Is. Here, since the non-foamed surface layer 23 in contact with the base material 2 or the preheating roll 7 is in a high temperature state in advance by preheating, the base material 2 and the non-foamed laminate film 3 are fixed with high strength by thermal laminating. Will be done. The thick arrow in FIG. 3 indicates the transport direction of the base material 2, the non-foamed laminated film 3, and the synthetic resin laminated foam sheet 1. Further, the heating roll 6 may be provided instead of the transport roll 83, and the pair of heating rolls 6 and 6 may be thermally laminated.

According to the first embodiment, the polyolefin-based resin layer 31 having a thickness of 40 μm or more of the non-foamed laminated film 3 suppresses heat from reaching the bonding interface between the non-foamed laminated film 3 and the base material 2. Can be done. Therefore, even when a high boiling point food such as a food containing oil is heated in a microwave oven with the non-foaming laminated film 3 on the food side, the heat due to the heating is suppressed from reaching the fixing interface of the film 3 and the non-foaming is prevented. It is possible to prevent peeling (derami) of the laminated film 3.

Further, by setting the peel strength of the non-foamed laminated film 3 to the base material 2 to 3.0 N / 15 mm or more, sufficient adhesive strength between the base material 2 and the non-foamed laminated film 3 can be ensured, and synthetic resin lamination can be ensured. When the food container 5 is heat-molded with the foamed sheet 1, the non-foamed laminated film 3 can be made to follow the base material 2 well, and the food container 5 having a complicated shape can be molded without generating delamination. Further, by ensuring sufficient adhesive strength between the base material 2 and the non-foaming laminated film 3, it is possible to more reliably prevent peeling (derami) of the non-foaming laminated film 3 even when heating in a microwave oven.

Further, according to the manufacturing method in which the base material 2 is preheated and then heat-laminated with a heating roll 6, the surface layer on the side to which the base material 2 is fixed is preheated in advance to a high temperature state, whereby the heat laminating is performed. It is possible to increase the bonding strength and the fixing strength between the base material 2 and the non-foamed laminated film 3. Further, by improving the adhesive strength between the base material 2 and the non-foamed laminated film 3, a more complicated food container 5 can be molded from the synthetic resin laminated foam sheet 1 without causing delamination.

Further, when the non-foamed surface layer 23 of the base material 2 corresponding to the surface layer on the side to which the base material 2 is fixed is a polyolefin resin having a melting point of 130 ° C. to 160 ° C., the melting point of the non-foamed surface layer 23 is 160. Since the temperature is below ° C, the adhesion between the base material 2 and the non-foamed laminate film 3 by thermal laminating can be ensured with excellent bonding strength and strength without using expensive equipment capable of high-temperature thermal laminating. Can be done. Further, since the melting point of the non-foamed surface layer 23 is 130 ° C. or higher, the non-foamed laminated film is formed when the food is placed in the food container 5 molded from the synthetic resin laminated foam sheet 1 and heated in a microwave oven. It is possible to more reliably prevent the peeling (derami) of 3 from occurring.

[Synthetic resin laminated foam sheet of the second embodiment and its manufacturing method, food container]
As shown in FIG. 4, the synthetic resin laminated foam sheet 1a according to the second embodiment of the present invention includes a base material 2a having a foamed layer 21a and a non-foamed laminated film 3a laminated on the base material 2a. be. The synthetic resin laminated foam sheet 1a is used as a material for a food container. For example, a food container having the same shape as the food container 5 of the first embodiment has a synthetic resin so that the non-foamed laminated film 3a is arranged on the food side. It is formed of a laminated foam sheet 1a.

The base material 2a in the synthetic resin laminated foam sheet 1a of the second embodiment is formed by laminating non-foamed surface layers 23a and 23a as outermost layers on both surfaces of the foamed layer 21a. The foamed layer 21a is appropriate as long as it does not deviate from the gist of the present invention like the foamed layer 21 of the first embodiment. For example, foamed polypropylene (foamed PP) obtained by foaming polypropylene with a foaming agent or heat-resistant polystyrene is foamed. A polyolefin-based foamed resin such as heat-resistant polypropylene foamed with an agent is used. Further, the non-foamed surface layer 23a is appropriate as long as it does not deviate from the gist of the present invention like the non-foamed surface layer 23 of the first embodiment, but it is preferable that the non-foamed surface layer 23a can suppress the shavings generated during sheet production. For example, a polyolefin resin such as polypropylene (PP) may be used.

The non-foamed laminated film 3a laminated on the base material 2a has the same configuration as the non-foamed laminated film 3 of the first embodiment, has a polyolefin-based resin layer 31a, and the polyolefin-based resin layer 31a has a thickness of 40 μm or more. Is formed of. The thickness of the polyolefin-based resin layer 31a is also preferably 40 μm to 80 μm, more preferably 45 μm to 70 μm. The polyolefin-based resin layer 31a is appropriate as long as it does not deviate from the gist of the present invention like the polyolefin-based resin 31 of the first embodiment, and is, for example, polypropylene (PP) such as unstretched polypropylene (CPP). In the non-foamed laminated film 3a, the printing layer 32a and the coating layer 33a are laminated in this order on one side of the polyolefin resin layer 31a, and the composition of the printing layer 32a and the coating layer 33a is the printing layer of the first embodiment. 32, which is the same as the coat layer 33.

The non-foamed laminated film 3a is fixed to the base material 2a so that the peel strength of the non-foamed laminated film 3a with respect to the base material 2a is 3.0 N / 15 mm or more. In the second embodiment, the coat layer 33a of the non-foamed laminate film 3a is arranged adjacent to the non-foamed surface layer 23a on one side of the base material 2a, and the coat layer 33a of the non-foamed laminate film 3a and the non-foamed base material 2a are not placed. The foamed surface layer 23a is fixed so as to melt into each other.

For manufacturing the synthetic resin laminated foam sheet 1a of the second embodiment, it is possible to use the same equipment as the manufacturing equipment of the synthetic resin laminated foam sheet 1 of the first embodiment shown in FIG. At the time of manufacturing, the base material 2a in a state in which the non-foamed surface layers 23a and 23a are laminated on both sides of the foamed layer 21a and integrated is conveyed by the conveying rolls 81 and 82, while the conveying roll 81 and the conveying roll 82 are conveyed. The base material 2a is preheated by the preheating roll 7 located between them. This preheating is performed at a temperature equal to or lower than the melting point of the non-foamed surface layer 23a of the base material 2a so that the non-foamed surface layer 23a does not melt. The temperature of the preheating is preferably 50 ° C. or higher, more preferably 60 ° C. or higher in the non-foamed surface layer 23a of the base material 2a. Further, at least one side of the non-foamed surface layer 23a on the side to be bonded to the non-foamed laminated film 3a or the base material 2a to be bonded to the non-foamed laminated film 3a, which will be described later, is preheated. Also in the second embodiment, it is preferable that the non-foamed surface layer 23a of the base material 2a is formed of a polyolefin resin having a melting point of 130 ° C. to 160 ° C., and more preferably a polyolefin resin having a melting point of 135 ° C. to 155 ° C. , More preferably, it is preferably formed of a polyolefin resin having a melting point of 140 ° C. to 150 ° C. In this case, it is preferable to preheat the preheating roll 7 so that the temperature of the preheating roll 7 is 100 to 140 ° C. and the temperature of the non-foamed surface layer 23a of the base material 2a is 80 to 120 ° C.

After that, the base material 2a is fed between the heating roll 6 and the transport roll 83 by the transport roll 82, and the non-foamed laminated film 3a is fed between the heating roll 6 and the transport roll 83 so as to be on the heating roll 6 side. The heating roll 6 and the transport roll 83 are laminated so as to sandwich the conveyed base material 2a and the non-foaming laminate film 3a, and are heated by the heating roll 6 to heat-laminate the base material 2a and the non-foaming laminate film 3a. do. The thermal laminating is performed by a heating roll 6 heated to a temperature equal to or higher than the melting point of the polyolefin resin layer 31a constituting the non-foaming laminate film 3a, and the base material 2a and the non-foaming laminate film 3a are welded or adhered by this heating. The temperature of the heating roll 6 is preferably 170 ° C. or higher, more preferably 200 ° C. or higher, and is preferably 170 to 250 ° C., although it depends on the thickness of the base material 2a non-foamed laminated film 3a and the pick-up speed for these. .. Here, since the non-foamed surface layer 23a in contact with the base material 2a or the preheating roll 7 is in a high temperature state in advance by preheating, the base material 2a and the non-foaming laminate film 3a are fixed with high strength by thermal laminating. Will be done.

According to the second embodiment, the corresponding effect can be obtained from the configuration corresponding to the first embodiment.

[Synthetic resin laminated foam sheet of the third embodiment and its manufacturing method, food container]
As shown in FIG. 5, the synthetic resin laminated foam sheet 1b according to the third embodiment of the present invention includes a base material 2b composed of a foamed layer 21b and a non-foamed laminated film 3b laminated on the base material 2b. It is a thing. The synthetic resin laminated foam sheet 1b is used as a material for a food container. For example, a food container having the same shape as the food container 5 of the first embodiment has a synthetic resin so that the non-foamed laminated film 3b is arranged on the food side. It is formed of a laminated foam sheet 1b.

The foamed layer 21b constituting the base material 2b in the synthetic resin laminated foam sheet 1b of the third embodiment is appropriate as in the case of the foamed layer 21 of the first embodiment within a range not deviating from the gist of the present invention, for example, polypropylene. Is foamed polypropylene (foamed PP) foamed with a foaming agent, polystyrene-based foamed resin such as heat-resistant PSP in which heat-resistant polystyrene is foamed with a foaming agent, and the like.

The non-foamed laminated film 3b laminated on the base material 2b has the same configuration as the non-foamed laminated film 3 of the first embodiment, has a polyolefin-based resin layer 31b, and the polyolefin-based resin layer 31b has a thickness of 40 μm or more. Is formed of. The thickness of the polyolefin resin layer 31b is also preferably 40 μm to 80 μm, more preferably 45 μm to 70 μm. The polyolefin-based resin layer 31b is appropriate as long as it does not deviate from the gist of the present invention like the polyolefin-based resin 31 of the first embodiment, and is, for example, polypropylene (PP) such as unstretched polypropylene (CPP). In the non-foamed laminated film 3b, a printing layer 32b and a coating layer 33b are laminated in this order on one side of a polyolefin resin layer 31b, and the composition of the printing layer 32b and the coating layer 33b is the printing layer of the first embodiment. 32, which is the same as the coat layer 33. When the base material 2b is a heat-resistant PSP, it is preferable to use a mixed material of urethane-based vehicle and acrylic-based vehicle as the coat layer 33.

The non-foamed laminated film 3b is fixed to the base material 2b so that the peel strength of the non-foamed laminated film 3b with respect to the base material 2b is 3.0 N / 15 mm or more. In the third embodiment, the coat layer 33b of the non-foaming laminate film 3b is adjacently arranged on one side of the base material 2b, and the coat layer 33b of the non-foaming laminate film 3b and the base material 2b are fixed so as to be melted together. ..

For manufacturing the synthetic resin laminated foam sheet 1b of the third embodiment, it is possible to use the same equipment as the manufacturing equipment of the synthetic resin laminated foam sheet 1 of the first embodiment shown in FIG. During manufacturing, the base material 2b composed of the foam layer 21b is conveyed by the transfer rolls 81 and 82, and the base material 2b is preheated by the preheating roll 7 located between the transfer roll 81 and the transfer roll 82. do. This preheating is performed at a temperature equal to or lower than the melting point of the foam layer 21b constituting the surface layer on the side to which the base material 2 is fixed so that the foam layer 21b constituting the surface layer does not melt. The temperature of the preheating is preferably 50 ° C. or higher, more preferably 60 ° C. or higher in the foamed layer 21b constituting the surface layer on the side to which the base material 2b is fixed. Further, at least the surface layer of the base material 2b to be bonded to the non-foamed laminate film 3b, which will be described later, is preheated. In the preheating, it is preferable to preheat the preheating roll 7 so that the temperature of the preheating roll 7 is 100 to 140 ° C. and the temperature of the surface layer of the base material 2b at least on the side to which the preheating roll 7 is fixed is 80 to 120 ° C.

After that, the base material 2b is fed between the heating roll 6 and the transport roll 83 by the transport roll 82, and the non-foamed laminate film 3b is fed between the heating roll 6 and the transport roll 83 so as to be on the heating roll 6 side. The heating roll 6 and the transport roll 83 are laminated so as to sandwich the conveyed base material 2b and the non-foaming laminate film 3b, and are heated by the heating roll 6 to heat-laminate the base material 2b and the non-foaming laminate film 3b. do. The thermal laminating is performed by a heating roll 6 heated to a temperature equal to or higher than the melting point of the polyolefin resin layer 31b constituting the non-foaming laminate film 3b, and the base material 2b and the non-foaming laminate film 3b are welded or adhered by this heating. The temperature of the heating roll 6 is preferably 170 ° C. or higher, more preferably 200 ° C. or higher, and is preferably 170 to 250 ° C., although it depends on the thickness of the base material 2b non-foamed laminated film 3b and the pick-up speed for these. .. Here, since the foamed layer 21b, which is the surface layer on the side to which the base material 2b is fixed, is in a high temperature state in advance by preheating, the base material 2b and the non-foamed laminated film 3b are fixed with high strength by thermal laminating. ..

According to the third embodiment, the corresponding effect can be obtained from the configuration corresponding to the first embodiment.

[Scope of inclusion of the invention disclosed in the present specification]
The invention disclosed in the present specification is specified by changing the partial contents thereof to other contents disclosed in the present specification to the extent applicable, in addition to the inventions listed as inventions and the embodiments. Or, those specified by adding other contents disclosed in the present specification to these contents, or those specified by deleting these partial contents to the extent that a partial action and effect can be obtained and making them into a higher concept. Including. The invention disclosed in the present specification also includes the following modifications and additional contents.

For example, in the base material 2 of the first embodiment, the non-foaming intermediate layers 22 and 22 are laminated on both surfaces of the foaming layer 21, and the non-foaming surface layers 23 and 23 are laminated on the outside of the respective non-foaming intermediate layers 22 and 22. However, the base material may be formed by laminating the non-foaming intermediate layer 22 on only one side of the foaming layer 21 and laminating the non-foaming surface layer 23 on the outside of the non-foaming intermediate layer 22. In this case, it is preferable that the non-foamed surface layer 23 side of this base material is the side to be fixed to the non-foamed laminate film 3.

Further, the base material 2a of the second embodiment is formed by laminating the non-foaming surface layers 23a and 23a as the outermost layers on both surfaces of the foaming layer 21a, but the non-foaming surface layer 23a is laminated only on one side of the foaming layer 21a. It may be used as a base material formed in the above process. In this case, it is preferable that the non-foamed surface layer 23a side of this base material is the side to be fixed to the non-foamed laminated film 3a.

Further, the synthetic resin laminated foam sheet of the present invention includes a non-foamed laminated film having one or more polyolefin-based resin layers and having a total thickness of 40 μm or more of the polyolefin-based resin layers, for example, FIG. As in the first modification and the second modification of the first embodiment shown in the above, the one having two polyolefin resin layers and the total thickness of the two polyolefin resin layers is 40 μm or more, or three layers. Those having the above-mentioned polyolefin-based resin layer and having a total thickness of three or more layers of the polyolefin-based resin layer of 40 μm or more are also included.

The synthetic resin laminated foam sheet 1m of the first modification of the first embodiment of FIG. 6A is a base material 2 having the same foam layer 21 as that of the first embodiment, and is not laminated on the base material 2. A foam laminated film 3 m is provided. The non-foamed laminated film 3 m is laminated and fixed on the base material 2, so that the peel strength of the non-foamed laminated film 3 m with respect to the base material 2 is 3.0 N / 15 mm or more, as in the first embodiment. And fixed.

The non-foamed laminated film 3m is obtained by laminating and fixing a coat layer 33m, a polyolefin resin layer 31m, an adhesive layer 34m, a printing layer 32m, and a polyolefin resin layer 35m in this order from the base material 2 side. The print layer 32 m and the coat layer 33 m have the same configuration as the print layer 32 and the coat layer 33 in the first embodiment. Further, the total thickness of the two polyolefin resin layers 31 m and 35 m is formed to be 40 μm or more, and the total thickness is preferably 40 μm to 80 μm, more preferably 45 μm to 70 μm. good. The polyolefin-based resin layers 31 m and 35 m are appropriate as long as they do not deviate from the gist of the present invention, and for example, each of them is polypropylene (PP) such as unstretched polypropylene (CPP). The adhesive layer 34m is formed of an olefin-based, polyurethane-based, polyester-based, or ether-based adhesive.

The synthetic resin laminated foam sheet 1 m of the first modification is used as a material for food containers as in the first embodiment, and is subjected to a step of preheating with a preheating roll 7 or the like and heat laminating with a heating roll 6. It is preferable to manufacture. The synthetic resin laminated foam sheet 1 m of the first modification corresponds to the first embodiment from the configuration corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment and the total thickness of the polyolefin resin layers 31 m and 35 m. It works.

The synthetic resin laminated foam sheet 1n of the second modification of the first embodiment of FIG. 6B is a base material 2 having the same foam layer 21 as that of the first embodiment, and is not laminated on the base material 2. A foam laminated film 3n is provided. The non-foamed laminated film 3n is laminated and fixed on the base material 2, so that the peel strength of the non-foamed laminated film 3n with respect to the base material 2 is 3.0 N / 15 mm or more, as in the first embodiment. It is fixed.

In the non-foamed laminated film 3n, a coat layer 33n, a printing layer 32n, a polyolefin resin layer 31n, an adhesive layer 34n, a gas barrier layer 36n, an adhesive layer 37n, and a poreolefin resin layer 35n are laminated and fixed in this order from the base material 2 side. It was done. The print layer 32n and the coat layer 33n have the same configuration as the print layer 32 and the coat layer 33 in the first embodiment. Further, the total thickness of the two layers of the polyolefin resin layers 31n and 35n is formed to be 40 μm or more, and the total thickness is preferably 40 μm to 80 μm, more preferably 45 μm to 70 μm. good. The polyolefin-based resin layers 31n and 35n are appropriate as long as they do not deviate from the gist of the present invention, and for example, each of them is polypropylene (PP), polyethylene (PE), a mixed material of PP and PE, or the like. The adhesive layers 34n and 37n are formed of an olefin-based, polyurethane-based, polyester-based, or ether-based adhesive. Further, the gas barrier layer 36n is appropriate as long as it can obtain gas barrier properties within a range not deviating from the gist of the present invention, for example, ethylene vinyl alcohol copolymer resin (EVOH), polyvinylidene chloride (PVDC), nylon ( NY), polyethylene terephthalate (PET) and the like, and the oxygen permeability of the material is 1,000 cc / 25 μm · m ² · day · atm or less.

The synthetic resin laminated foam sheet 1n of the second modification is used as a material for food containers as in the first embodiment, and is subjected to a step of preheating with a preheating roll 7 or the like and heat laminating with a heating roll 6. It is preferable to manufacture. The synthetic resin laminated foam sheet 1n of the second modification corresponds to the first embodiment from the configuration corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment and the total thickness of the polyolefin resin layers 31 m and 35 m. It works. Furthermore, when the non-foaming laminate film is placed on the food side and the food containing oil is heated in a microwave oven by the gas barrier layer 36n, the high-temperature substance flowing out of the food and its heat are fixed to the non-foaming laminate film 3n. It is possible to more reliably prevent the non-foamed laminated film from reaching the interface and more reliably prevent the non-foamed laminated film from peeling off (derami).

Further, as the non-foamed laminated film 3, 3a, 3b, 3m, and 3n, those having an easy peel property as a characteristic may be used. The method for producing the non-foamed laminated films 3, 3a, 3b, 3m, and 3n is appropriate, such as dry laminating and coextrusion. Further, when the synthetic resin laminated foam sheet of the present invention is used for a food container, foods include cooked foods such as prepared foods and various edible foods such as foodstuffs, and in particular, the temperature is 100 ° C. or higher when heated in a microwave oven. High boiling point foods (foods with a fat content of 1% or more on the surface of foods and foods other than dried solid foods (oil-based foods), or spices in foods or on the surface of foods with a content of 0.5% or more) , Foods other than dried solid foods (foods containing spices), etc.), and examples of high-boiling foods include curry and mabo tofu. Further, as this spice component, cumin, coriander, clove, cinnamon, cardamom, nutmeg, all spice, caraway, fennel, phenugrine, turmeric, saffron, paprika and the like are applicable. When high-boiling foods (especially curry and mapo tofu) are heated in a microwave oven, the temperature rises locally, and the oil and fat components or spice components contained in the high-boiling foods form a coating agent due to the adhesion between the base material and the laminated film. It may deteriorate and promote derami. Therefore, increasing the thickness of the polyolefin-based resin layer has a great effect on preventing delamination in that the oil / fat component or the spice component does not penetrate into the coating agent. The synthetic resin laminated foam sheet of the present invention is highly effective when used in a food container for accommodating such high boiling point foods. Further, the base material in the present invention is a heat-resistant base material (a 100 mm × 100 mm test piece is prepared, heated in a constant temperature bath at 100 ° C. for 1 hour in a stationary state, heated and then taken out and cooled at room temperature for 1 hour. The length is measured, and the value obtained by subtracting the length after heating from the length before heating is divided by the length before heating multiplied by 100, and the value is 5 or less, more preferably 2 or less). Then, it is possible to prevent the container from being deformed when heated in a microwave oven, which is preferable. Further, when the foamed layer of the base material or the heat-resistant base material in the present invention is a polypropylene foamed layer, the heat resistance is higher than that of the polystyrene foamed layer, so that the container can be prevented from being deformed even when overheated in a microwave oven. It is suitable to be made.

[Example and comparative example]
Next, examples and comparative examples of the food container molded from the synthetic resin laminated foam sheet of the present invention will be described.

Example 1 in Table 1 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and the foam layer of the base material constituting the food container is polypropylene. Was foamed with a foaming agent (foamed PP), the non-foamed intermediate layer was polypropylene containing talc (PP), the non-foamed surface layer was polypropylene (PP), and the thickness of the entire substrate was 1.0 mm. .. The polyolefin-based resin layer constituting the non-foamed laminate film arranged inside the food container is unstretched polypropylene (CPP) having a thickness of 50 μm, the printing layer is a urethane-based vehicle, and the coating layer is a chlorinated PP-based coating agent. did. Since the printed layer and the coat layer are only slightly thicker than the polyolefin resin layer, the thickness of the non-foamed laminate film is 50 μm, which is almost the same as the thickness of the polyolefin resin layer of unstretched polypropylene (CPP). be. The base material constituting the food container of Example 1 and the non-foamed laminated film are fixed with a peel strength of 4.0 N / 15 mm or more. The peel strength of this non-foamed laminated film is the peel strength test specified in the test standard: JIS K 6854-2, the testing machine: the seal peeling tester manufactured by Fuji Impulse Co., Ltd., the testing machine setting: the distance between chucks is 25 mm, and the peeling speed. : The test piece was cut out from the food container from the edge to the side at 200 mm / min, and the same applies to each Example and Comparative Example described later.

Example 2 in Table 1 below is a food container molded by using a synthetic resin laminated foam sheet corresponding to 1 m of the synthetic resin laminated foam sheet of the first modification of the first embodiment, and is a base material constituting the food container. The configuration and thickness of the above are the same as those of the first embodiment. In the non-foamed laminate film placed inside the food container, the coat layer is chlorinated PP-based coating agent in order from the base material side, and the polyolefin-based resin layer closer to the base material is bonded with 25 μm thick unstretched polypropylene (CPP). The layer was a polyolefin adhesive, the printing layer was a urethane vehicle, and the polyolefin resin layer exposed and arranged inside the food container was unstretched polypropylene (CPP) having a thickness of 25 μm. The total thickness of the two layers of unstretched polypropylene (CPP) polyolefin resin layers is 50 μm, and the coat layer, adhesive layer, and printed layer are only slightly thicker than the polyolefin resin layer. The thickness of the non-foamed laminated film is 50 μm, which is substantially the same as the total thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). The peel strength between the base material constituting the food container of Example 2 and the non-foamed laminated film is also 4.0 N / 15 mm or more.

Example 3 in Table 1 below is a food container molded by using the synthetic resin laminated foam sheet 1n corresponding to the synthetic resin laminated foam sheet 1n of the second modification of the first embodiment, and is a base material constituting the food container. The configuration and thickness of the above are the same as those of the first embodiment. In the non-foamed laminate film placed inside the food container, the coat layer is a chlorinated PP-based coating agent, the printing layer is a urethane-based vehicle, and the polyolefin-based resin layer closer to the base material is polypropylene with a thickness of 20 μm in order from the base material side. (PP), the adhesive layer near the base material is a polyolefin adhesive, the gas barrier layer is an EVOH resin with a thickness of 5 μm, the adhesive layer near the inside of the food container is a polyolefin adhesive, and it is placed exposed inside the food container. The polyolefin resin layer was made of polypropylene (PP) having a thickness of 25 μm. Since the coat layer, adhesive layer, and print layer are only slightly thicker than the polyolefin-based resin layer, the thickness of the non-foamed laminate film is the thickness of the two-layer polypropylene (PP) polyolefin-based resin layer and the gas barrier. It is substantially the same as the total thickness of 50 μm, which is the total thickness of the layers. The peel strength between the base material constituting the food container of Example 3 and the non-foamed laminated film is also 4.0 N / 15 mm or more.

In Example 4 in Table 1 below, the polyolefin-based resin layer exposed and arranged inside the food container in Example 3 is replaced with polypropylene (PP) having a thickness of 25 μm, and polypropylene having a thickness of 25 μm ( It is a mixture of PP) and polyethylene (PE), and other configurations are the same as in Example 3.

In Example 5 in Table 1 below, a polypropylene (PP) -based resin for extrusion lamination having a thickness of 20 μm is used instead of the coat layer in Example 1, and the resin is further exposed to the inside of the food container in Example 1. The thickness of the unstretched polypropylene (CPP) to be arranged is 30 μm instead of 50 μm. Other configurations are the same as those in the first embodiment. Since the total thickness of the polyolefin-based resin layer is 50 μm, which is the total of these two layers, and the printed layer is only slightly thicker than the polyolefin-based resin layer, the thickness of the non-foamed laminated film is these polyolefins. The thickness is 50 μm, which is substantially the same as the total thickness of the based resin layer.

Example 6 in Table 1 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1a of the second embodiment, and the foam layer of the base material constituting the food container is polypropylene. Was foamed with a foaming agent (foamed PP), the non-foamed surface layer was polypropylene (PP), and the thickness of the entire substrate was 1.0 mm. Further, the configuration of the non-expanded laminated film arranged inside the food container is the same as that of the first embodiment, and the thickness of the non-expanded laminated film is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). It is 50 μm. The base material constituting the food container of Example 6 and the non-foamed laminated film are also fixed with a peel strength of 4.0 N / 15 mm or more.

Example 7 in Table 1 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1b of the third embodiment, and the foam layer of the base material constituting the food container is heat resistant. The PSP was used, and the thickness of the entire base material was 3.5 mm. Further, the configuration of the non-expanded laminated film arranged inside the food container is the same as that of the first embodiment, and the thickness of the non-expanded laminated film is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). It is 50 μm. A mixture of urethane-based vehicle and acrylic-based vehicle was used for the coat layer of the foamed laminated film in Example 7. The base material constituting the food container of Example 7 and the non-foamed laminated film are also fixed with a peel strength of 4.0 N / 15 mm or more.

Example 8 in Table 2 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and is a polyolefin constituting the non-foamed laminated film of Example 1. The based resin layer is made of unstretched polypropylene (CPP) having a thickness of 40 μm instead of unstretched polypropylene (CPP) having a thickness of 50 μm. The thickness of the non-foamed laminated film is 40 μm, which is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). Other configurations are the same as those in the first embodiment.

In Example 9 in Table 2 below, the polyolefin-based resin layer constituting the non-foamed laminate film of Example 1 is replaced with unstretched polypropylene (CPP) having a thickness of 50 μm instead of unstretched polypropylene (CPP) having a thickness of 45 μm. It was done. The thickness of the non-foamed laminated film is 45 μm, which is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). Other configurations are the same as those in the first embodiment.

In Example 10 in Table 2 below, the polyolefin-based resin layer constituting the non-foamed laminate film of Example 1 is replaced with unstretched polypropylene (CPP) having a thickness of 50 μm instead of unstretched polypropylene (CPP) having a thickness of 70 μm. It was done. The thickness of the non-foamed laminated film is 70 μm, which is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). Other configurations are the same as those in the first embodiment.

In Example 11 in Table 2 below, the polyolefin-based resin layer constituting the non-foamed laminate film of Example 1 is replaced with unstretched polypropylene (CPP) having a thickness of 50 μm instead of unstretched polypropylene (CPP) having a thickness of 80 μm. It was done. The thickness of the non-foamed laminated film is 80 μm, which is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). Further, the base material constituting the food container of Example 11 and the non-foamed laminated film are fixed with a peel strength of 3.0 N / 15 mm or less. Other configurations are the same as those in the first embodiment.

In Comparative Example 1 in Table 2 below, the polyolefin-based resin layer constituting the non-foamed laminate film of Example 1 is replaced with unstretched polypropylene (CPP) having a thickness of 50 μm and unstretched polypropylene (CPP) having a thickness of 25 μm. It was done. The thickness of the non-foamed laminated film is 25 μm, which is substantially the same as the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP). Other configurations are the same as those in the first embodiment.

Regarding Examples 1 to 11 and Comparative Example 1, the heat resistance due to the presence or absence of deformation of the container, the presence or absence of peeling of the non-foamed laminated film (presence or absence of delamination), and the shapeability by molding were evaluated. In terms of heat resistance, the food container was heated in a constant temperature bath (“DK600” manufactured by Yamato Kagaku Co., Ltd.) at 100 ° C. for 1 hour in a stationary state, and after heating, it was taken out and cooled at room temperature for 1 hour. confirmed. In the evaluation of heat resistance, ○ indicates no deformation of the container, Δ indicates that there is slight deformation but there is no functional problem, and × indicates that the container is deformed. Regarding the presence or absence of peeling of the non-foamed laminated film, curry, which is an oily food, was packed in a food container and heated in a microwave oven at 1,900 W for one and a half minutes. It was visually confirmed whether or not it was. In the evaluation of peeling of the non-foamed laminated film, ◯ indicates no deflation, Δ indicates that deflation occurred in some parts, and × indicates that deflation occurred. As for the formability by molding, it was visually confirmed whether the non-foamed laminated film followed the base material when the synthetic resin laminated foam sheets in Examples 1 to 11 and Comparative Example 1 were molded into a food container. In the evaluation of formability by molding, ○ indicates that the non-foamed laminated film follows the substrate during molding, △ indicates that the non-foamed laminated film follows the substrate during molding, but there is a risk that it does not follow, × Is a non-foamed laminated film that did not follow the substrate during molding.

In Examples 1 to 5, Examples 7, and Examples 9 to 10, the heat resistance due to the presence or absence of container deformation, the presence or absence of peeling of the non-foamed laminated film (presence or absence of delamination), and the shapeability by molding are all evaluated as ○. It can be seen that the synthetic resin laminated foam sheet and the food container are excellent in heat resistance, peeling prevention performance of the non-foamed laminated film, and shapeability by molding. In Example 6, it seemed that the heat resistance was lowered due to the absence of the non-foaming intermediate layer from the visual state, but the container deformation itself did not occur. In Example 8, since the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP) was relatively thin, it seemed that there was a risk of delamination from a visual state, but delamination itself did not occur. .. On the other hand, in Comparative Example 1, since the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP) was as thin as 25 μm, heat was transferred to the bonding interface between the base material and the non-foamed laminated film, and delamination was generated. .. In Example 11, the thickness of the polyolefin-based resin layer of unstretched polypropylene (CPP) is thick, and due to this thickness, the adhesive strength between the base material and the non-foamed laminate film due to the thermal laminating is lowered, and the non-foamed laminate at the time of molding is reduced. It is considered that the followability of the film is deteriorated, but the non-foamed laminated film followed the substrate at the time of molding.

Next, the evaluation when the melting points of the non-foamed surface layers of the base material in the synthetic resin laminated foam sheet are different will be described. In Example 1 in Table 1 and Table 3 below, the melting point of polypropylene (PP) constituting the non-foamed surface layer of the base material is 147 ° C. Further, in the production of the synthetic resin laminated foam sheets of Examples 1 and Examples 12 to 15 described later, a step of heat laminating with a heating roll after the above-mentioned preheating was used, and the surface temperature of the preheated base material was 100 ° C. The temperature of the heating roll was set to 230 ° C.

Example 12 in Table 3 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and polypropylene (polypropylene) constituting the non-foamed surface layer of the base material. The melting point of PP) is 135 ° C. Other configurations are the same as those in the first embodiment.

Example 13 in Table 3 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and polypropylene (polypropylene) constituting the non-foamed surface layer of the base material. The melting point of PP) is 155 ° C. Further, the base material constituting the food container of Example 13 and the non-foamed laminated film are fixed with a peel strength of 3.0 N / 15 mm or more. Other configurations are the same as those in the first embodiment.

Example 14 in Table 3 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and polypropylene (polypropylene) constituting the non-foamed surface layer of the base material. The melting point of PP) is 165 ° C. Further, the base material constituting the food container of Example 14 and the non-foamed laminated film are fixed with a peel strength of 3.0 N / 15 mm or less. Other configurations are the same as those in the first embodiment.

Example 15 in Table 3 below is a food container molded by using the synthetic resin laminated foam sheet corresponding to the synthetic resin laminated foam sheet 1 of the first embodiment, and polypropylene (polypropylene) constituting the non-foamed surface layer of the base material. The melting point of PP) is 125 ° C. Other configurations are the same as those in the first embodiment.

In Examples 12 and 15, the heat resistance and the formability at the time of molding are good, but the melting point of the non-foamed surface layer is relatively low, so that there is a risk of delamination from a visual state. It seemed to be there, but the derami itself did not occur. Further, in Examples 13 and 14, while the heat resistance and the delamination prevention performance are good, the melting point of the non-foamed surface layer is relatively high and the amount of heat at the time of thermal laminating is insufficient. It is considered that the adhesive strength between the material and the non-foamed laminated film is lowered and the followability of the non-foamed laminated film at the time of molding is lowered, but the non-foamed laminated film follows the base material at the time of molding.

The present invention can be used, for example, when forming a food container for containing food.

1, 1a, 1b, 1m, 1n ... Synthetic resin laminated foam sheet 2, 2a, 2b ... Base material 21, 21a, 21b ... Foam layer 22 ... Non-foam intermediate layer 23, 23a ... Non-foam surface layer 3, 3a, 3b 3, 3m, 3n ... Non-foamed laminated film 31, 31a, 31b, 31m, 35m, 31n, 35n ... Polyolefin resin layer 32, 32a, 32b, 32m, 32n ... Printing layer 33, 33a, 33b, 33m, 33n ... Coat Layers 34m, 34n, 37n ... Adhesive layer 36n ... Gas barrier layer 5 ... Food container 6 ... Heating roll 7 ... Preheating roll 81, 82, 83, 84 ... Conveying roll

Claims (4)

It contains a foam layer, a non-foamed intermediate layer made of polypropylene containing an inorganic filler laminated on one or both sides of the foamed layer, and an inorganic filler laminated on the outside of the non-foamed intermediate layer. With a substrate composed of a non-foamed surface layer made of no polypropylene ,
A synthetic resin laminated foam sheet comprising a non-foamed heat laminated film laminated on the non-foamed surface layer of the base material.
A synthetic resin laminated foam sheet, wherein the non-foaming heat laminated film has one or more polypropylene resin layers , and the total thickness of the polypropylene resin layers is 40 μm or more. The synthetic resin laminated foam sheet according to claim 1, wherein the peel strength of the non-foamed heat laminated film with respect to the base material is 3.0 N / 15 mm or more. The method for manufacturing a synthetic resin laminated foam sheet according to claim 1 or 2.
The first step of preheating the non-foamed surface layer on the side where the base material adheres to the non-foamed heat laminated film to a temperature equal to or lower than the melting point of the non-foamed surface layer.
It is characterized by comprising a second step of heat laminating the base material and the non-foaming heat laminating film by a heating roll heated to a temperature equal to or higher than the melting point of the polypropylene resin layer constituting the non-foaming heat laminating film. A method for manufacturing a synthetic resin laminated foam sheet. A food container formed of the synthetic resin laminated foam sheet according to claim 1 or 2, wherein the non-foamed heat laminated film is arranged on the food side.

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